Design: Pragmatic 2×2 factorial randomised trial
Population: 1,837 adults due for annual lung cancer screening after a normal scan
Primary outcome: Completion of screening CT 9–15 months after the index scan
Effect: Stepped reminders 75.5% vs 47.4%; RR 1.59 (95% CI 1.47–1.72)

A pragmatic two-by-two factorial trial at a US health system randomised 1,837 people who had a normal low-dose CT for lung cancer screening, and were due for their annual scan, to usual care, education materials, stepped reminders, or both. Stepped reminders meant a coordinator pended the scan order for the primary care physician to sign and then contacted the patient to book it.

Adherence to annual screening was 75.5% with stepped reminders against 47.4% without (RR 1.59). The gain was larger in current smokers, 73% against 41%. Education in print and video, on its own, slightly reduced adherence, 59.2% against 63.3%.

The lesson travels beyond lung screening: the work that improved adherence was taking the task off the busy clinician and patient, not explaining the test better. Any recall programme, whether for diabetic eye screening, surveillance colonoscopy or annual lung CT, can borrow the design. India has no national lung screening programme, so the direct application is limited, but the recall principle applies to every surveillance list a physician keeps.

Use a registry and coordinator to identify patients due for repeat screening rather than relying on memory.
Pre-prepare the order for the clinician to sign, then contact the patient to book.
Prioritise outreach to current smokers, who gained most from reminders.
Do not rely on leaflets or videos alone to bring patients back for surveillance.

Why it matters

It shows that the barrier to repeat screening is logistics, not knowledge.

The statistics, in plain English

A relative risk of 1.59 means patients receiving stepped reminders were about 60% more likely to complete their scan. The tight interval (1.47 to 1.72) makes the effect robust. The education arm's small negative effect had an interval touching 1.00, so it may be chance.